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Human Physiology and exercise > Week 7 > Flashcards

Week 7 Flashcards

1
Q

Key information about smooth muscle

A

Cells form layers and line the cavities of hollow organs
Contractions are controlled by the autonomic nervous system
Cells are connected to eath other electrically and mechanically

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2
Q

How are smooth muscles arranged
What does this arrangement allow them to do

A

Smooth muscles have no sarcomere.
The actin and mysoin filaments are arranged in the form of a lattice around the cell, allowing the smooth muscle to change shape

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3
Q

Dense bodies

A

Actin filaments attach to the cell via specialised areas in the cytoplasm called the dense bodies

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4
Q

Dense bands

A

Smooth muscle cells are mechanically connected to neighbouring cells via specialised areas on the membrane called dense bands

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5
Q

How are smooth muscles activated

A

There are no neuromuscular junctions
The neurotransmitter is released from varicosities

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6
Q

Difference between the activation of a single unit smooth muscle and a multi unit smooth muscle

A

Single unit - cells are electrically coupled by gap junctions and function as a unit
Multi-unit - cells are not electrically coupked
Each cell needs to be activated by a nerve

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7
Q

How can smooth muscle be activated

A

Rhythmically by pacemaker potentials or by acute events that pushes the balance of excitation and inhibition above threshold

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8
Q

No sarcomere arrangement means that

A

Myosin and actin can slide past each other without entering the end of a sarcomere

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9
Q

Role of calcium in smooth muscle

A

No troponin in smooth muscle so actin binding sites always available
Calcium source is from the sarcoplasmic reticulum or extracelluar sources which activates calmodulin, which activates myosin light chain kinase

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10
Q

Calcium acts on ______________ as opposed to _____________

A

Thick filaments as opposed to thin filaments

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11
Q

Relaxation of smooth muscle

A

Happens by myosin light chain phosphatase
If it overwhelms the activation of muscle due to not enough calcium then the muscle will relax and vice versa

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12
Q

What is cardiac output
What is the abbreviation
What are the units
How is it calculated

A

Cardiac output is the volume of blood pumped out by the heart every minute
Q
ml or l so the units are ml/min or l/min
Heart rate x stroke volume

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13
Q

What happens to CO, HR and SV when workload increases

A

HR has a linear relationship
SV decreases with more workload as heart has less time to refill
This pushes cardiac output down as workload increases

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14
Q

How does the parasympathetic system slow heart rate

A

Parasympathetic nerve endings (vagus nerve) secretes the neurotransmitter acetylcholine

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15
Q

How does the sympathetic system increases heart rate

A

Sympathetic fibres (cardiac nerves) supply the SA and AV nodes and increase HR by releasing norepinephrine

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16
Q

Stroke volume is regulated by two opposing factors

A

The force by which the muscle cells contract
The arterial pressure against which they have to eject the blood

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17
Q

The force of contraction is regulated by two processes

A

The length-tension properties of cardiac muscle cells and the effects of hormonal influence on the contractility of cardiac muscle

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18
Q

Starlings law

A

Increases in venous return
Greater diastolic filling of the heart
Increased chamber elasticity
Increased ejection fraction
Increased force of contraction
Increased stroke volume

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19
Q

To have an increase in cardiac output, what is required

A

Increase in HR
Increase in SV

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20
Q

For heart rate to increase, what has to happen

A

Vagus nerve activity decreases
Sympathetic nerve activity to increase
Circulatory epinephrine increases

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21
Q

For stroke volume to increase, what needs to happen

A

End diastolic volume to increase
Circulating epinephrine increases
Sympathetic nerve activity to increase

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22
Q

What is blood pressure

A

Driving force for flow in the cardiovascular system

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23
Q

What must blood pressure be?

A

It must be regulated, so that it is high enough to create flow, but not too high to put excessive stress on the cardiovascular system

24
Q

Equipment used to measure blood pressure

A

Inflatable cuff
Pressure gauge
Stethoscope

25
Q

When the cuff pressure is below diastolic pressure

A

Blood flows freely and there is no sound

26
Q

When the cuff pressure is above systolic pressure (>120mm Hg)

A

There is no blood flow and no sound as you have collapsed the arteries

27
Q

As you slowly lower the cuff pressure to between systolic and diastolic pressure (80-120 mm Hg)

A

There is intermittent flow and tapping sounds

28
Q

As you lower the pressure further to below diastolic pressure

A

You loose the sound, telling you the diastolic blood pressure

29
Q

How is mean arterial pressure calculated

A

Mean arterial pressure is calculated from the values of systolic and diastolic blood pressure, but it is not an average of the two
Diastole lasts almost twice as long as systole therefore MAP is weighted more heavily towards the diastolic blood pressure value

30
Q

How to calculate MAP

A

MAP = diastolic + (systolic-diastolic / 3)

31
Q

Normal blood pressure values, and mean arterial pressure

A

Normal blood pressure for systolic is 120 mmHg, 80 mmHg for diastolic and 93 mmHg for mean arterial pressure

32
Q

Why does blood pressure increase with age

A

Arteries become stiffer with age due to loss of elasticity
Arteries less able to expand and due to blood supply being the same, blood pressure increases with age

33
Q

On average, women have ______ blood pressure than men throughout their lives

A

Lower

34
Q

Pressure is higher in the foot and lower in the head due to

A

Hydrostatic pressure

35
Q

In dynamic exercise, mean blood pressure remains relatively steady
Why?

A

There is an increase in systolic pressure (demand for blood rises) but also a reduction in diastolic pressure - due to arteries being more relaxing and welcoming of blood

36
Q

Conversely, in static exercise (lifting weights) mean blood pressure rises dramatically

A

Yep

37
Q

Role of the adevntitia

A

Provides structural strength and tethers the vessels in place
In large vessels, the adventitia is so large, it has its own blood supply

38
Q

Elastin

A

Give vessels mechanical strength and their elastic properties (expand and recoil)

39
Q

Endothelium

A

The endothelial layer is the filtering interface between the blood and the body

40
Q

Smooth muscle

A

Supplies the vessels with contractile power and regulates the diameter of the lumen

41
Q

Pre capillary sphincter

A

Controls blood flow to specific capillary beds selectively

42
Q

Active hyperaemia

A

The increase in blood flow according to the metabolic needs of the tissue in question

43
Q

Flow autoregulation

A

Concerned with the maintenance of blood flow rather than changing it. When the driving pressure drops, the vessels dilate, and when it increases the vessels constrict

44
Q

Factors that affect arterial diameter
-Neural controls

A

Neural controls
-vasoconstrictors - sympathetic nerves that release norepinephrine
-vasodilators - neurones that release nitric oxide

45
Q

Factors that affect arterial diameter
-Hormonal controls

A

Vasoconstrictors - epinephrine, vasopressin
Vasodilators - epinephrine

46
Q

Factors that affect arterial diameter
-Local controls

A

Vasoconstrictors - internal blood pressure
Vasodilators -
Decreased o2

47
Q

What is special about epinephrine

A

It can cause vasodilation or vasoconstriction depending on what receptors it binds onto

48
Q

Fick’s law of diffusion for capillaries

A

Flow of gas = area/ thickness x D X (P2-P1)

49
Q

Types of capillary arrangement

A

Continuous - cells tightly packed
Fenestrated - have tiny openings
Discontinuous - large gaps to allow red blood cells through

50
Q

2 forces that compete for fluid regulation in a capillary

A

Hydrostatic pressure forces fluid out of the capillary
Colloid osmotic pressure of proteins within the capillary pulls fluid into the capillary

51
Q

Net pressure =

A

Hydrostatic pressure - colloid osmotic pressure

52
Q

Difference between a vein and an artery

A

Veins have
Larger diameters
Less elastic tissue
Less smooth muscle
Are more distensible
Thinner walls
Valves

53
Q

Difference between a healthy vein and a diseased vein

A

In healthy veins, flow is only towards the heart. Backflow is prevented by shut valves
In a diseased vein, leaky valves allow blood to move in the opposite direction causing blood to accumulate in the extremities

54
Q

Skeletal muscle pump

A

Compression of veins by muscle contraction empties them of blood towards the heart

55
Q

Respiratory pump

A

Creates a pressure difference between the abdomen and the thoracic cavity that promotes blood return to the heart

Human Physiology and exercise (12 decks)

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